building air cannon: is it better to have the air chamber in a straight line with the barrel?does it affect performance?

I've been reading a lot of information air cannons, some say it's better to have the chamber, directly and back up the barrel for best performance.some say it doesn't matter, it's all in the trigger mechanism. What is the best, piston or sprinkler valve? Thanks I actually do have a lot more questions but I feel the need to be brief.

Darwil8 years ago
An air chamber in line to the barrel is the most efficient in terms of energy produced and therefor air useage - but is more difficult to valve. If you have the Air chamber a right angles to the barrel this is the best compromise, but keep the air port as short as possible. The best type of valve to use is a "knock open valve" where the air is released by a sprung hammer knocking the valve off its seat - this needs more engineering but the results are worth the trouble. I have been involved in making an air cannon that was used for testing Olympic javelins - our first results propelled the javelins over more than 2 football pitches!!! Take care with your air pressures - Gas or divers bottles work best but you will need a single stage regulator to turn the pressure down. We used 400 psi with a 2" diameter barrel initially (too much power) and ended up with 300 psi. Good luck take care.
Genises8 years ago
makes no difference, think about it high pressure after a bend means nothing because all of the air is at the same pressure so no matter where the air is released the force will be the same. look at a balloon if you stab it on one side it explodes with the exact same force as it would have if you you stabbed it on the other side
I would think that an air chamber directly behind the barrel would result in a less restricted, straight shot of air. But the gun would be stupid long. I don't know the actual math behind how much two 90 degree elbows would slow down the air but I would guess it wouldn't really matter that much unless you are some pro building it for a serious purpose. As for the sprinkler valve. Not sure about brands or anyhting but i've read that one that opens fast and that you can actuate by a battery (opposed to a ball valve getting turned by hand) Good luck with your build man. I hear air cannons can be pretty insane!.